Icinga ADD second master in master zone - icinga2.state - migration

Hi,
I have a very large setup (see below), and I have tried to setup a secondary icinga core node on “master” zone HA.
When I started the new master; all services that were in downtime, on ack state, and passive checks, triggered new alert notifications, causing a most unwanted noise on my organization.

as a workaround, I stopped the new master,
copied over the /var/lib/icinga2/icinga2.state file from the other master
and restarted icinga2 service, which eventually stopped sending out the notifications.

Question is:
Can you tell if there is some sort of migration tool so that I can start the new master without disrupting NOC team operations, with notifications for services that were already handled.?

is this copy/paste safe to do? or do I get anything corrupted as a consequence of ?

Can you tell the contents of the icinga2.state file and the modified.attributes file?

Can you tell how if this icinga2.state file will come in sync, so that when I stop former master (i.e. patching), whichever updates occur on new master via api (downtime, acks) wil be replicated to former master on startup (without further touching on my part?)

Thanks in advance

validation output

[2020-11-18 12:45:48 +0000] information/cli: Icinga application loader (version: 2.11.3-1)
[2020-11-18 12:45:48 +0000] information/cli: Loading configuration file(s).
[2020-11-18 12:45:49 +0000] information/ConfigItem: Committing config item(s).
[2020-11-18 12:45:59 +0000] information/WorkQueue: #4 (DaemonUtility::LoadConfigFiles) items: 4, rate: 6.06667/s (364/min 364/5min 364/15min); empty in 18584 days, 12 hours, 45 minutes and 59 seconds
[2020-11-18 12:46:09 +0000] information/WorkQueue: #4 (DaemonUtility::LoadConfigFiles) items: 4, rate: 6.06667/s (364/min 364/5min 364/15min); empty in infinite time, your task handler isn't able to keep up

[2020-11-18 12:47:27 +0000] information/ConfigItem: Instantiated 112 ScheduledDowntimes.
[2020-11-18 12:47:27 +0000] information/ConfigItem: Instantiated 299 HostGroups.
[2020-11-18 12:47:27 +0000] information/ConfigItem: Instantiated 1 EventCommand.
[2020-11-18 12:47:27 +0000] information/ConfigItem: Instantiated 1 FileLogger.
[2020-11-18 12:47:27 +0000] information/ConfigItem: Instantiated 3 NotificationCommands.
[2020-11-18 12:47:27 +0000] information/ConfigItem: Instantiated 1 NotificationComponent.
[2020-11-18 12:47:27 +0000] information/ConfigItem: Instantiated 98414 Notifications.
[2020-11-18 12:47:27 +0000] information/ConfigItem: Instantiated 1 IcingaApplication.
[2020-11-18 12:47:27 +0000] information/ConfigItem: Instantiated 6237 Hosts.
[2020-11-18 12:47:27 +0000] information/ConfigItem: Instantiated 112802 Dependencies.
[2020-11-18 12:47:27 +0000] information/ConfigItem: Instantiated 1 CheckerComponent.
[2020-11-18 12:47:27 +0000] information/ConfigItem: Instantiated 61 Zones.
[2020-11-18 12:47:27 +0000] information/ConfigItem: Instantiated 76 Endpoints.
[2020-11-18 12:47:27 +0000] information/ConfigItem: Instantiated 1 ApiUser.
[2020-11-18 12:47:27 +0000] information/ConfigItem: Instantiated 423 CheckCommands.
[2020-11-18 12:47:27 +0000] information/ConfigItem: Instantiated 6 TimePeriods.
[2020-11-18 12:47:27 +0000] information/ConfigItem: Instantiated 1 UserGroup.
[2020-11-18 12:47:27 +0000] information/ConfigItem: Instantiated 3 Users.
[2020-11-18 12:47:27 +0000] information/ConfigItem: Instantiated 89136 Services.
[2020-11-18 12:47:27 +0000] information/ConfigItem: Instantiated 51 ServiceGroups.
[2020-11-18 12:47:27 +0000] information/ScriptGlobal: Dumping variables to file '/var/cache/icinga2/icinga2.vars'
[2020-11-18 12:47:27 +0000] information/cli: Finished validating the configuration file(s).

Package/OS information

pesantos@monitoring-icinga-master-1.localdomain ~$ cat /etc/centos-release
CentOS Linux release 7.8.2003 (Core)
pesantos@monitoring-icinga-master-1.localdomain ~$ uname -a
Linux monitoring-icinga-master-1.localdomain 3.10.0-1127.19.1.el7.x86_64 #1 SMP Tue Aug 25 17:23:54 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
pesantos@monitoring-icinga-master-1.localdomain ~$ sudo rpm -qa | grep icinga
icinga2-2.11.3-1.el7.icinga.x86_64
icinga2-bin-2.11.3-1.el7.icinga.x86_64
icinga2-common-2.11.3-1.el7.icinga.x86_64
icinga2-ido-mysql-2.11.3-1.el7.icinga.x86_64

``

I’m closing this issue.
It is documented on github.